In the field of non-impact printing, the most common types of printers have been the thermal printer and the ink jet printer. When the performance of a non-impact printer is compared with that of an impact printer, one of the problems in the non-impact machine has been the control of the printing operation. As is well-known, the impact operation depends upon the movement of impact members such as wires or the like and which are typically moved by means of an electromechanical system which is believed to enable a more precise control of the impact members.
The advent of non-impact printing, as in the case of thermal printing, brought out the fact that the heating cycle must be controlled in a manner to obtain maximum repeated operations. Likewise, the control of ink jet printing in at least one form thereof must deal with rapid starting and stopping movement of the ink fluid from a supply of the fluid. In each case, the precise control of the thermal elements and of the ink droplets is necessary to provide for both correct and high speed printing.
In the matter of ink jet printing, it is extremely important that the control of the ink droplets be precise and accurate from the time of formation of the droplets to depositing of such droplets on paper or like record media, and to make certain that a clean printed character results from the ink droplets. While the method of printing with ink may be performed in a continuous manner or in a demand pulse manner, the latter method is disclosed in the present application as applying the features of the present invention. The drive means for the ink droplets is generally in the form of a crystal element to provide the high speed operation for ejecting the ink through the nozzle while allowing time between droplets for proper operation. The ink nozzle construction must be of a nature to permit fast and clean ejection of ink droplets from the print head.
It is therefore proposed to provide a nozzle plate on the print head to maintain high speed ink jet printing.
Representative prior art in the field of ink jet print head nozzles includes German Application No. 2,024,330, of T. Yanou et al., opened to the public on Nov. 26, 1970. This publication discloses an ink jet printer having a nozzle formed as a capillary tube of glass and a water repellent coating on the tube except for the front edge surface thereof.
German Application No. 2,434,794, of R. Strecker opened to the public on Feb. 5, 1976, discloses an ink jet print head having a nozzle plate of dielectric material and provided with a pair of electrodes, one electrode at the beginning and the other electrode at the end of the nozzle.
German Application No. 2,460,131, of H. Sicking et al. opened to the public on July 1, 1976, discloses an ink jet print head and a process for making a nozzle plate and including coating the outer surface of the plate as well as the inner cylindrical surface to eliminate the roughness of the surfaces.
German Application No. 2,728,657, of E. Kattner, opened to the public on Jan. 4, 1979, and corresponding to U.S. Pat. No. 4,209,794, discloses a nozzle plate for an ink jet print head wherein the orifices each have an ink input area and a tapered acceleration area.
U.S. Pat. No. 3,921,916, issued to E. Bassous on Nov. 25, 1975, discloses a method of producing fluid nozzles in monocrystalline silicon utilizing anisotropic etching through the silicon to an integral etch-resistant barrier layer in a semiconductor wafer.
U.S. Pat. No. 3,949,410, issued to E. Bassous et al. on Apr. 6, 1976, discloses a jet nozzle design in a crystalline semiconductor block of silicon with an electrode structure which is integrally incorporated therewith and whereby a variable electric field is established near the orifice of the jet nozzle structure.
U.S. Pat. No. 4,007,464, issued to E. Bassous et al. on Feb. 8, 1977, discloses an array of nozzles formed by etching a semiconductor wafer of silicon. The nozzles are each in the shape of a truncated pyramid with the entrance and exit apertures being substantially square in cross-section.
And, U.S. Pat. No. 4,112,436, issued to D. R. Cone on Sept. 5, 1978, discloses a glass nozzle array for an orifice plate formed with a plurality of glass tubes and cemented in epoxy between two parallel glass plates and wherein spaced supports of oriented silicon are etched to form the grooves to align the glass tubes.